For many, the first stroke comes as a big surprise. Some have had no history of heart disease. Their blood pressure and weight were good. They avoided unhealthy, cholesterol-rich foods such as cheeseburgers and French fries. They were doing all the right things to reduce their stroke risk. Then they're told they are at risk for a second stroke.
Now a major research study suggests a way to dramatically cut the risk of a second stroke by putting even more of a squeeze on a familiar culprit — cholesterol.
High cholesterol has been linked with heart disease and stroke. With stroke, having a high blood cholesterol can increase your risk for ischemic stroke, the most common type of stroke. Ischemic stroke is caused by blocked blood flow to the brain, often due to a build-up of plaque in the blood vessels and blood clots blocking the vessel. Statin drugs, also known as “clot busters,” have been used for years to lower cholesterol in people with heart disease risks. A new study has found that the use of statin drugs also reduces the risk of repeat ischemic strokes.
no history of heart disease
- already following a stroke prevention plan in a normal cholesterol range
- Their risk of a repeat stroke fell 16 percent when they further reduced their cholesterol with LipitorŪ (atorvastatin), a specific statin drug.
“The results are very significant — what we call a robust figure,” said Dr. Michael Welch, the lead researcher of the international study, which followed 4,732 men and women for seven years. Welch is president and CEO of Rosalind Franklin University of Medicine and Science in North Chicago.
The relationship between stroke and cholesterol, never studied on this depth or magnitude before, is called the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL). Referred to informally as “the sparkle study,” the nickname is a reflection of the enthusiasm Welch and his team feel over its results.
“Now we have another bullet in the arsenal against stroke,” Welch said.
Pfizer, Inc., the maker of LipitorŪ, financed the study but had no influence over the outcome, according to Welch. The results were rechecked by multiple layers of independent committees known for their rigorous impartiality and inability to be swayed.
Cholesterol is a naturally occurring, fatty substance that lines the cells and is necessary to maintain life. It's created by a liver enzyme and also by diet. In recent years, research has shown there's “good” cholesterol (HDL) and also an evil twin, the so-called “bad cholesterol” (LDL), which is believed to impact the vessel walls.
Today, the relationship between “bad” cholesterol and heart attack is appreciated even by the general public. But until the SPARCL study, the link between cholesterol and stroke had been somewhat weak.
Welch said it's important to note that SPARCL's good news involves patients with no history of heart disease who have had an ischemic (clot-caused) stroke.
For those suffering clot-related strokes, the key finding from the SPARCL data is that “even (by) reducing a normal cholesterol level you protect your patients against having another stroke,” he said.
Thus, the SPARCL results suggest that after a first stroke, patients should include statins as part of their routine management, Welch said. Statins are a class of drugs that block the enzyme in the liver that makes cholesterol. Welch said it's unlikely the same level of reduction could be achieved by diet alone.
In the general population, Welch points out the bar for “normal” cholesterol levels has shifted downward in recent years. He said current guidelines suggest that if you have risk of heart attack, your “bad” blood cholesterol level should be maintained at about 100. Those at risk of diabetes should go even lower, to about 70.
While the SPARCL data suggests statin drugs help reduce the number of repeat strokes caused by clots, the outcome is different for hemorrhagic strokes, which are caused by a blood vessel bursting and blood seeping into the brain. For these strokes, further research is needed.
SPARCL showed that the incidence of hemorrhagic stroke, compared to the general population, actually increased slightly when patients used the statin drug. “It's a very small risk but that's a concern,” Welch said.
Meanwhile, more inroads are being made into the way cholesterol impacts stroke. The thinking was that cholesterol built up on artery walls and narrowed them. Now it's believed that cholesterol build-up causes the lining of the artery to break down and form an ulcer, Welch said. That's where the clot begins to form.
“The important point is we've been very successful in preventing stroke by management of risk factors,” he said. These risk factors include high blood pressure and diabetes, as well as weight control, regular exercise and maintaining a healthy diet.
And now, there's evidence that reducing cholesterol with statin use works, too. “This is a totally new approach,” he said.
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